An antenna for mobile communication and satellite broadcasting needs to function to change the beam direction (referred to as “beam scanning” or “beam steering”). As an example of the antenna (hereinafter referred to as a “scanning antenna”) having such a function, a phased array antenna including antenna units is known. However, an existing phased array antenna is expensive, which is an obstacle for popularization as a consumer product. Particularly, as the number of antenna units increases, the cost rises considerably.
Therefore, a scanning antenna utilizing high dielectric anisotropy (birefringence index) of a liquid crystal material (including nematic liquid crystals and polymer dispersed liquid crystals) has been proposed (PTL 1 to PTL 4 and NPL 1). Since a dielectric constant of a liquid crystal material has frequency dispersion, a dielectric constant in a frequency band of microwaves (may be referred to as a “dielectric constant with respect to microwaves”) is particularly referred to as a “dielectric constant M(εM)” herein.
PTL 3 and NPL 1 each describe an inexpensive scanning antenna that can be obtained by utilizing liquid crystal display (hereinafter referred to as “LCD”) device technology.